1. To represent a single, longer sound:
* Examples: * "happy" (the "pp" makes a single, longer "p" sound)
* "better" (the "tt" makes a single, longer "t" sound)
* "runner" (the "nn" makes a single, longer "n" sound)
2. To indicate the pronunciation of a vowel before it:
* Examples: * "kitten" (the "tt" helps pronounce the "i" as a short "i" sound)
* "letter" (the "tt" helps pronounce the "e" as a short "e" sound)
* "hammer" (the "mm" helps pronounce the "a" as a short "a" sound)
It's important to note that double consonants can also be used in words that were originally spelled with a single consonant but have evolved over time, such as "grass" and "dinner".